Ultrasound catheter devices and methods

ABSTRACT

Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions. Generally, ultrasound catheters include an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and a distal head coupled with the transmission member and positioned adjacent the distal end of the catheter body for disrupting occlusions. Improved features of ultrasound catheters include prevention of independent rotation of the ultrasound transmission member, a safety anchor for the distal head, a one-piece transmission member/distal head and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/493,430, filed Jul. 25, 2006, entitled “METHOD OF MANUFACTURING ANULTRASOUND TRANSMISSION MEMBER FOR USE IN AN ULTRASOUND CATHETER,” whichis a divisional of U.S. patent application Ser. No. 10/410,617, filedApr. 8, 2003, entitled “ULTRASOUND CATHETER DEVICES AND METHODS,” whichissued as U.S. Pat. No. 7,220,233 on May 22, 2007, both of which areincorporated herein by reference. This application is also related tothe following pending U.S. patent applications, the full disclosures ofwhich are all hereby incorporated by reference: U.S. patent applicationSer. No. 10/229,371, filed Aug. 26, 2002, entitled “ULTRASOUND CATHETERFOR DISRUPTING BLOOD VESSEL OBSTURCTIONS;” U.S. patent application Ser.No. 10/345,078, filed Jan. 14, 2003, entitled “ULTRASOUND CATHETER ANDMETHODS FOR MAKING AND USING SAME;” and U.S. patent application Ser. No.10/375,903, filed Feb. 26, 2003, entitled “ULTRASOUND CATHETERAPPARATUS.”

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods.More specifically, the present invention relates to ultrasound catheterdevices and methods for treating occlusive intravascular lesions.

Catheters employing various types of ultrasound transmitting membershave been successfully used to ablate or otherwise disrupt obstructionsin blood vessels. Specifically, ablation of atherosclerotic plaque orthromboembolic obstructions from peripheral blood vessels such as thefemoral arteries has been particularly successful. Various ultrasoniccatheter devices have been developed for use in ablating or otherwiseremoving obstructive material from blood vessels. For example, U.S. Pat.Nos. 5,267,954 and 5,380,274, issued to an inventor of the presentinvention and hereby incorporated by reference, describe ultrasoundcatheter devices for removing occlusions. Other examples of ultrasonicablation devices for removing obstructions from blood vessels includethose described in U.S. Pat. No. 3,433,226 (Boyd), U.S. Pat. No.3,823,717 (Pohlman, et al.), U.S. Pat. No. 4,808,153 (Parisi), U.S. Pat.No. 4,936,281 (Stasz), U.S. Pat. No. 3,565,062 (Kuris), U.S. Pat. No.4,924,863 (Sterzer), U.S. Pat. No. 4,870,953 (Don Michael, et al), andU.S. Pat. No. 4,920,954 (Alliger, et al.), as well as other patentpublications WO87-05739 (Cooper), WO89-06515 (Bernstein, et al.),WO90-0130 (Sonic Needle Corp.), EP, EP316789 (Don Michael, et al.),DE3,821,836 (Schubert) and DE2438648 (Pohlman). While many ultrasoundcatheters have been developed, however, improvements are still beingpursued.

Typically, an ultrasonic catheter system for ablating occlusive materialincludes three basic components: an ultrasound generator, an ultrasoundtransducer, and an ultrasound catheter. The generator converts linepower into a high frequency current that is delivered to the transducer.The transducer contains piezoelectric crystals which, when excited bythe high frequency current, expand and contract at high frequency. Thesesmall, high-frequency expansions and contractions have both longitudinaland transverse components (relative to an axis of the transducer and thecatheter), which are amplified by the transducer horn into vibrationalenergy. The vibrations are then transmitted from the transducer throughthe ultrasound catheter via an ultrasound transmission member (or wire)running longitudinally through the catheter. The transmission membertransmits the vibrational energy to the distal end of the catheter wherethe energy is used to ablate or otherwise disrupt a vascularobstruction.

To effectively reach various sites for treatment of intravascularocclusions, ultrasound catheters of the type described above typicallyhave lengths of about 150 cm or longer. To permit the advancement ofsuch ultrasound catheters through small and/or tortuous blood vesselssuch as the aortic arch, coronary vessels, and peripheral vasculature ofthe lower extremities, the catheters (and their respective ultrasoundtransmission wires) must typically be sufficiently small and flexible.Due to attenuation of ultrasound energy along the long, thin, ultrasoundtransmission wire, a sufficient amount of vibrational energy must beapplied at the proximal end of the wire to provide a desired amount ofenergy at the distal end.

An ultrasound transmission wire is usually coupled at its proximal endwith the transducer by means of a sonic connector. The sonic connectortypically has a significantly larger diameter than that of theultrasound transmission member, the difference in diameters helping toamplify the vibrational energy being transmitted from the transducer tothe transmission wire. Several different means have typically been usedfor connecting the ultrasound transmission wire with the transducer viathe sonic connector, such as complementary threads, pressure fitting andthe like. One shortcoming of currently available devices is that theymay allow the transmission wire to rotate independently from thecatheter body. In these devices, it is not possible to rotate theultrasound transmission wire by rotating, for example, a proximal handleor sonic connector assembly, since the transmission wire rotates freelyand independently of the catheter body and such a proximal assembly.

Another potential drawback of currently available devices is that theyoften to not include optimal means for removing particles that arebroken up or dislodged by the catheter. Yet another possible shortcomingis that many ultrasound catheter devices include a distal tip, asmentioned above, but do not have means for preventing the distal tipfrom migrating from the device into the patient's body if the tipbreaks. Similarly, most ultrasound transmission members include multiplecomponents for transmitting vibrational energy, which causes stresses atthe connection points of the multiple components during use andpotential breakage of the ultrasound transmission wire or othercomponents. Also, ultrasound transmission wires are often exposed toincreased amounts of stress due to one or more bends in patientvasculature, causing increased wear and tear on the transmission wire.

Therefore, a need exists for improved ultrasound catheter devices andmethods that provide ablation or disruption of vascular occlusions.Ideally, such ultrasound catheters would include means for reducing oreliminating rotational motion of the ultrasound transmission wirerelative to the catheter body. It would also be advantageous to haveultrasound catheters which included means for removing particles,preventing distal tip and ultrasound transmission wire migration,preventing stress at component connection points and/or preventingstress at bends in the catheter. Such catheter devices would ideally besufficiently thin and flexible to be advanced through narrow, tortuousvasculature, such as the coronary vasculature, while also beingconfigured to enhance the usable life of the ultrasound transmissionwire. At least some of these objectives will be met by the presentinvention.

SUMMARY OF THE INVENTION

Ultrasound catheter devices and methods provide enhanced disruption ofblood vessel obstructions. Generally, ultrasound catheters include anelongate flexible catheter body with one or more lumens, an ultrasoundtransmission member extending longitudinally through the catheter bodylumen and a distal head coupled with the transmission member andpositioned adjacent the distal end of the catheter body for disruptingocclusions. Improved features of ultrasound catheters include preventionof independent rotation of the ultrasound transmission member, a safetyanchor for the distal head, a one-piece transmission member/distal headand the like.

In one aspect of the invention, an ultrasound catheter for disruptingocclusions in blood vessels comprises: an elongate flexible catheterbody having a proximal end, a distal end and at least one lumen; anultrasound transmission member extending longitudinally through thelumen of the catheter body and having a proximal end and a distal end; adistal head coupled with the distal end of the ultrasound transmissionmember and disposed adjacent the distal end of the catheter body; asonic connector coupled with the proximal end of the ultrasoundtransmission member for coupling the ultrasound transmission member withan ultrasound transducer device; and a connector housing coupled withthe proximal end of the catheter body for housing the sonic connectorand a proximal portion of the ultrasound transmission wire and forpreventing the ultrasound transmission member from rotating relative tothe catheter body.

In some embodiments, the connector housing comprises a sonic connectorcavity for holding the sonic connector to prevent it from rotatingrelative to the connector housing. Also in some embodiments, theultrasound transducer device includes an ultrasound transducer housinghaving a proximal end and a distal end. In such embodiments, theconnector housing may optionally be coupled with the distal end of theultrasound transducer housing via coupling means allowing for manualcoupling without using coupling tools. In one embodiment, the connectorhousing is coupled with the distal end of the ultrasound transducerhousing via complementary threads on the two housings. Alternatively,the connector housing may be coupled with the distal end of theultrasound transducer housing via pressure fitting. In some of theseembodiments, the ultrasound transducer housing further comprises atleast one protrusion on its distal end and a slidable collar for fittingover the at least one protrusion to press a portion of the distal end ofthe ultrasound transducer housing against the connector housing, therebyfurther securing the ultrasound transducer housing to the connectorhousing.

In another aspect, an ultrasound catheter for disrupting occlusions inblood vessels comprises: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end and a distal end; a distal headcoupled with the distal end of the ultrasound transmission member anddisposed adjacent the distal end of the catheter body; a sonic connectorcoupled with the proximal end of the ultrasound transmission member forcoupling the ultrasound transmission member with an ultrasoundtransducer device; and a rotation control member coupled with theproximal end of the catheter body for preventing the ultrasoundtransmission member from rotating relative to the catheter body.Optionally, the rotation control member may comprise a connector housingfor housing the sonic connector and a proximal portion of the ultrasoundtransmission member. In some of such embodiments, the connector housingmay comprise a sonic connector cavity for holding the sonic connector toprevent it from rotating relative to the connector housing. Also in someembodiments, the ultrasound transducer device includes an ultrasoundtransducer housing having a proximal end and a distal end. Again, theconnector housing may be coupled, in some embodiments, with the distalend of the ultrasound transducer housing via coupling means allowing formanual coupling without using coupling tools. Such coupling may be bycomplementary threads on the two housings, pressure fitting or the like.In some embodiments, the ultrasound transducer housing further comprisesat least one protrusion on its distal end and a slideable collar forfitting over the at least one protrusion to press a portion of thedistal end of the ultrasound transducer housing against the connectorhousing, thereby further securing the ultrasound transducer housing tothe connector housing.

In yet another aspect, an ultrasound catheter for disrupting occlusionsin blood vessels comprises: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end and a distal end; a distal headcoupled with the distal end of the ultrasound transmission member anddisposed adjacent the distal end of the catheter body; a sonic connectorcoupled with the proximal end of the ultrasound transmission member forcoupling the ultrasound transmission member with an ultrasoundtransducer device; and means for coupling the sonic connector with theultrasound transducer device while preventing the ultrasoundtransmission member from rotating relative to the catheter body. In someembodiments, the means for coupling comprises a housing for securing thesonic connector to prevent it from rotating relative to the housing.

In another aspect, an ultrasound catheter system for disruptingocclusions in blood vessels comprises: an elongate flexible catheterbody having a proximal end, a distal end and at least one lumen; anultrasound transmission member extending longitudinally through thelumen of the catheter body and having a proximal end and a distal end; adistal head coupled with the distal end of the ultrasound transmissionmember and disposed adjacent the distal end of the catheter body; asonic connector coupled with the proximal end of the ultrasoundtransmission member; a connector housing having a proximal end and adistal end, the distal end coupled with the proximal end of the catheterbody, for housing the sonic connector and a proximal portion of theultrasound transmission wire and for preventing the ultrasoundtransmission member from rotating relative to the catheter body; and anultrasound transducer device removably couplable with the sonicconnector and the proximal end of the connector housing.

In some embodiments, the ultrasound transducer device includes anultrasound transducer housing comprising at least one protrusion on adistal end of the ultrasound transducer housing and a slideable collarfor fitting over the at least one protrusion to press a portion of thedistal end of the ultrasound transducer housing against the connectorhousing, thereby further securing the ultrasound transducer housing tothe connector housing. In some embodiments, the at least one protrusioncomprises a first ring member at least partially encircling a portion ofthe ultrasound transducer housing. Sometimes the first ring member mayinclude at least one longitudinal slot which narrows when the slideablecollar is fitted over the first ring member to reduce an inner diameterof the first ring member. In some embodiments, the collar comprises asecond ring member with an inner diameter to fit over at least part ofthe first ring member. In many embodiments, the slideable collar isslideable between an uncoupled position in which it does not contact theat least one protrusion and a coupled position in which it fits over theat least one protrusion. In some of these embodiments, the slideablecollar does not overlap the connector housing when the collar isdisposed in the coupled position or the uncoupled position.

In yet another aspect, an ultrasound catheter for disrupting occlusionsin blood vessels comprises: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end and a distal end; a distal headcoupled with the distal end of the ultrasound transmission member anddisposed adjacent the distal end of the catheter body; and at least oneanchor member for anchoring the distal head to at least a part of theultrasound catheter. In some embodiments, the at least one anchor memberis coupled with the distal head and the catheter body. In someembodiments, the at least one anchor member is coupled with the catheterbody closer to the distal end of the body than the proximal end of thebody. Alternatively, the at least one anchor member may be coupled withthe catheter body closer to the proximal end of the body than the distalend of the body. In other embodiments, the at least one anchor member iscoupled with the distal head and a guidewire tube, the guidewire tubedisposed within the catheter body and coupled with the catheter body. Inyet other embodiments, the at least one anchor member comprises aguidewire tube disposed within the catheter body and coupled with thecatheter body. In some embodiments, the at least one anchor member iscoupled with at least one of the distal head and the catheter body bymeans selected from the group consisting of bonding, welding, fusing,tying and heat shrinking. In some embodiments, the at least one anchormember comprises at least one of a metal and a polymer.

In another aspect, an ultrasound catheter for disrupting occlusions inblood vessels, comprises: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end, a distal end and a distal head,wherein the distal head and the rest of the ultrasound transmissionmember are manufactured from one piece of material; and a sonicconnector coupled with the proximal end of the ultrasound transmissionmember for coupling the ultrasound transmission member with anultrasound transducer device. In some embodiments, the ultrasoundtransmission member comprises at least one material having superelasticproperties. Also in some embodiments, the distal head of the ultrasoundtransmission member comprises at least one longitudinal aperture. Forexample, the at least one longitudinal aperture may comprise at leastone of an irrigation aperture and a guidewire aperture. In someembodiments, the ultrasound transmission member tapers from a largerdiameter at its proximal end to a smaller diameter adjacent the distalhead.

In another aspect, an ultrasound catheter for disrupting occlusions inblood vessels, includes: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end and a distal end, the ultrasoundtransmission member comprising a metal alloy including at least twometal components and having a tensile strength of between 170,000 Psiand 250,000 Psi; and a distal head coupled with the distal end of theultrasound transmission member and disposed adjacent the distal end ofthe catheter body, the distal head having an average density not toexceed 5 g/cm³. In some cases, the metal alloy comprises a superelasticalloy. For example, the superelastic alloy may be capable of elongationof between 7% and 17% in some embodiments. In one embodiment, thesuperelastic alloy comprises a nickel-titanium alloy having a nickelcontent of between 50.50 and 51.50 atomic weight. Optionally, thesuperelastic alloy may have a superelastic temperature range of between10° C. and 50° C.

In still another aspect, an ultrasound catheter for disruptingocclusions in-blood vessels includes: an elongate flexible catheter bodyhaving a proximal end, a distal end and at least one lumen, the catheterbody comprising at least in part a polymeric material having a flexuralmodulus of elasticity of less than 160 Psi; an ultrasound transmissionmember extending longitudinally through the lumen of the catheter bodyand having a proximal end and a distal end; a distal head coupled withthe distal end of the ultrasound transmission member and disposedadjacent the distal end of the catheter body; and a sonic connectorcoupled with the proximal end of the ultrasound transmission member forcoupling the ultrasound transmission member with an ultrasoundtransducer device. In some embodiments, the polymeric material comprisesa polymeric block amide. In some embodiments, the polymeric block amidehas a Shore D hardness value of between about 55 and about 75.Alternatively, the polymeric block amide may have a Shore D hardnessvalue of between about 25 and about 55. Also in some embodiments, 5% orless of the polymeric material may comprise a colorant.

In another aspect of the invention, a method of manufacturing anultrasound transmission member for use in an ultrasound catheter deviceinvolves: providing a generally cylindrically-shaped transmission membermaterial; shaping the material to taper the transmission member from afirst, wider end toward a second, narrower end; and forming a distalhead at the second, narrower end. In some cases, providing the materialcomprises providing a polymer having superelastic properties. Shapingthe material, in some embodiments, comprises grinding the material.Forming the distal head, in some embodiments, comprises forming abullet-shaped head. Optionally, forming the distal head may furthercomprise forming at least one longitudinal aperture through the head toprovide for passage of at least one of a guidewire and irrigation fluid.

In another aspect, a method for disrupting an occlusion in a bloodvessel includes: positioning an ultrasound catheter in the blood vesselsuch that a distal end of the catheter is adjacent the occlusion;transmitting ultrasound energy to an ultrasound transmission member ofthe ultrasound catheter to disrupt the occlusion into multiple occlusionfragments; expanding an expandable balloon coupled with the ultrasoundcatheter at a location proximal to the distal end of the catheter; andremoving at least some of the occlusion fragments from the blood vesselvia the ultrasound catheter. In some embodiments, positioning theultrasound catheter comprises guiding the catheter using a guidewire.Optionally, the occlusion fragments may be removed through at least oneaperture in a catheter body of the ultrasound catheter. In someembodiments, for example, the at least one aperture is in fluidcommunication with at least one irrigation lumen and the occlusionfragments are removed through the at least one aperture and the at leastone irrigation lumen. Alternatively, the at least one aperture may be influid communication with at least one guidewire lumen and the occlusionfragments are removed through the at least one aperture and the at leastone guidewire lumen. In another embodiment, the occlusion fragments areremoved through a sheath disposed around a portion of the ultrasoundcatheter. In any such embodiments, removing the occlusion fragments maycomprise applying a vacuum force to guide the fragments into at leastone aperture on the ultrasound catheter. For example, applying thevacuum may comprise using at least one of a syringe and a vacuum pump.

In another aspect of the invention, a method for disrupting an occlusionin a blood vessel comprises: introducing an ultrasound catheter into theblood vessel through a guide catheter; positioning the ultrasoundcatheter such that a distal end of the catheter is adjacent theocclusion; transmitting ultrasound energy to an ultrasound transmissionmember of the ultrasound catheter to disrupt the occlusion into multipleocclusion fragments; expanding an expandable balloon coupled with theguide catheter at a location proximal to the distal end of the catheter;and removing at least some of the occlusion fragments from the bloodvessel via the ultrasound catheter. Optionally, introducing andpositioning the ultrasound catheter may further comprise guiding thecatheter using a guidewire.

In yet another aspect, a method for disrupting an occlusion in a bloodvessel involves: positioning an ultrasound catheter in the blood vesselsuch that a distal end of the catheter is adjacent the occlusion;introducing at least one radiopaque fluid into the blood vessel throughat least one aperture in the ultrasound catheter adjacent the distal endto enhance visualization of a location of the distal end; andtransmitting ultrasound energy to an ultrasound transmission member ofthe ultrasound catheter to disrupt the occlusion into multiple occlusionfragments. Optionally, introducing the radiopaque fluid may compriseintroducing through at least one irrigation aperture in the ultrasoundcatheter. Alternatively, introducing the radiopaque fluid may compriseintroducing through at least one guidewire aperture in the ultrasoundcatheter. In yet other embodiments, introducing the radiopaque fluidcomprises introducing through a sheath surrounding a portion of theultrasound catheter and forming the at least one aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a system including an ultrasoundcatheter device and ultrasound energy source according to an embodimentof the present invention;

FIG. 2 is a perspective view of a proximal housing, sonic connector andultrasound transmission member of an ultrasound catheter deviceaccording to an embodiment of the present invention;

FIG. 3 is a cross-sectional side view of an ultrasound catheter deviceaccording to an embodiment of the present invention;

FIGS. 4A and 4B are cross-sectional side views of a proximal portion ofan ultrasound catheter device coupled with a distal end of an ultrasoundtransducer device, showing a collar in unengaged (FIG. 4A) and engaged(FIG. 4B) positions according to an embodiment of the present invention;

FIGS. 5A and 5B are perspective views of an ultrasound catheter devicecoupled with a distal end of an ultrasound transducer device, showing acollar in unengaged (FIG. 5A) and engaged (FIG. 5B) positions accordingto an embodiment of the present invention;

FIG. 6 is a side view of an ultrasound catheter device with a balloonand apertures for irrigation and suction according to an embodiment ofthe present invention;

FIG. 7 is a side view of an ultrasound catheter device with a balloonand apertures for irrigation and suction according to another embodimentof the present invention;

FIG. 8 is a side view of an ultrasound catheter device with a balloonand apertures for irrigation and suction according to still anotherembodiment of the present invention;

FIG. 9 is a cross-sectional side view of a distal end of an ultrasoundcatheter device with an anchor member according to an embodiment of thepresent invention;

FIG. 10 is a cross-sectional side view of a distal end of an ultrasoundcatheter device with an anchor member according to another embodiment ofthe present invention;

FIG. 11 is a cross-sectional side view of a distal end of an ultrasoundcatheter device with an anchor member according to still anotherembodiment of the present invention; and

FIGS. 12A-12C illustrate a method of manufacturing an ultrasoundtransmission member for use in an ultrasound catheter device accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Ultrasound catheter devices and methods of the present invention maygenerally be used for treating occlusions in blood vessels. Catheterdevices generally include a catheter body, an ultrasound energytransmission member disposed within the catheter body and a distal headcoupled with the energy transmission member and disposed at or near thedistal end of the catheter body. The ultrasound transmission membertransmits ultrasound energy from an ultrasound transducer to the distalhead, causing the head to vibrate and, thus, disrupt vascularocclusions. A number of improved features of such ultrasound catheterdevices are described more fully below.

Referring now to FIG. 1, one embodiment of an ultrasound catheter system20 suitably includes an ultrasound catheter device 10, including aproximal end connector 12 for coupling device 10 with an ultrasoundtransducer 14, and an ultrasound generator 16 coupled with transducer 14and a foot-actuated on/off switch 18 to provide ultrasonic energy totransducer 14 and, thus, to ultrasound catheter 10. Generally, catheter10 includes an ultrasound transmission member, or wire (not shown), fortransmitting energy from the transducer 14 to a distal head 26 ofcatheter 10. In some embodiments, transducer 14 further includes asecuring device 15 for enhancing coupling of catheter 10 to transducer14. Components of system 20 may be coupled via any suitable means, suchas connecting wires of any kind, wireless connections or the like.

In addition to proximal connector 12, ultrasound catheter device 10 mayinclude one or more other various components, such as a Y-connector 11or the like for providing access for irrigation, guidewire passage,suction or the like. Some embodiments of device include a rapid exchangeguidewire 13, some include a proximal guidewire port 17 for over thewire guidewire deliver, and some embodiments include both. In someembodiments, Y-connector may include an irrigation port, for providingaccess for an irrigation tube 24. Irrigation tube 24, in someembodiments, may be used for introducing one or more fluids, applyingvacuum, or both. Generally, catheter device 10 may include any suitablenumber of side-arms or ports for passage of a guidewire, infusing and/orwithdrawing irrigation fluid, dye and/or the like, or any other suitableports or connections. Also, ultrasound catheters 10 of the presentinvention may be used with any suitable proximal devices, such as anysuitable ultrasound transducer 14, ultrasound generator 16, couplingdevice(s) and/or the like. Therefore, exemplary FIG. 1 and any followingdescriptions of proximal apparatus or systems for use with ultrasoundcatheters 10 should not be interpreted to limit the scope of the presentinvention as defined in the appended claims.

Referring now to FIG. 3, a cross-sectional side view of one embodimentof ultrasound catheter device 10 is shown. Generally, ultrasoundcatheter 10 suitably includes an elongate catheter body 22 with anultrasound transmission member 24 disposed longitudinally through acatheter lumen 21 and ending in distal head (not shown). Catheter body22 is generally a flexible, tubular, elongate member, having anysuitable diameter and length for reaching a vascular occlusion fortreatment. In one embodiment, for example, catheter body 22 preferablyhas an outer diameter of between about 0.5 mm and about 5.0 mm. In otherembodiments, as in catheters intended for use in relatively smallvessels, catheter body 22 may have an outer diameter of between about0.25 mm and about 2.5 mm. Catheter body 22 may also have any suitablelength. As discussed briefly above, for example, some ultrasoundcatheters have a length in the range of about 150 cm. However, any othersuitable length may be used without departing from the scope of thepresent invention. Examples of catheter bodies similar to those whichmay be used in the present invention are described in U.S. Pat. Nos.5,267,954 and 5,989,208, which were previously incorporated herein byreference.

In some embodiments, catheter body 22 is made from a polymeric material.Sometimes the polymer will have a desired amount of flexibility, such asin one embodiment where catheter body 22 is made of a polymer having aflexural modulus of less than about 160 Psi. In some embodiments, such apolymer will be one of any number of polyether block amides, althoughother polymers may of course be used. In some embodiments, suchpolyether block amides may have a Shore D hardness value ranging fromabout 55 to about 75, while in other embodiments they may have a Shore Dhardness value ranging from about 25 to about 55. In some embodiments,the polymeric material includes up to about 5 weight percent of acolorant.

In most embodiments, ultrasound transmission member 24, wire, or waveguide extends longitudinally through catheter body lumen 21 to transmitultrasonic energy from ultrasound transducer 14, connected to theproximal end of catheter 10, to the distal end of catheter 10.Ultrasound transmission member 24 may be formed of any material capableof effectively transmitting ultrasonic energy from ultrasound transducer14 to the distal end of catheter body 22, including but not limited tometals such as pure titanium or aluminum, or titanium or aluminumalloys.

With continued reference to FIG. 3, one embodiment of proximal endconnector 12 suitably includes a housing 42 with a hollow inner bore 44.Bore 44 may have a uniform inner diameter along its length or,alternatively, may have multiple segments, such as a proximal segment47, a middle segment 45 and a distal segment 49, each of which maysurround one or more various components of proximal end connector 12.Generally, proximal segment 47 of bore 44 is configured to allowcoupling with ultrasound transducer 14 (not shown) via any suitablecoupling means, such as a pressure fit, complementary threads or thelike. Proximal segment 47 includes a sonic connector 52 for transmittingvibrational energy from transducer 14 to ultrasound transmission member24. Sonic connector 52 may be held within housing 42 by any suitablemeans. In some embodiments, for example, a dowel pin may extend throughsonic connector 52 to hold it within housing 42.

In another embodiment, and with reference now to FIG. 2, sonic connector52 may be secured within housing 42 by means of a cavity 202 in housing42. Cavity 202, in some embodiments, will have a complementary shape tosonic connector 52, such that sonic connector 52 fits snugly withincavity 202 to prevent rotation of sonic connector 52 independent ofhousing 42. In FIG. 2, for example, sonic connector 52 has flat sides204 which correspond with the shape of cavity 202. Any other suitableshape/configuration is contemplated. By preventing free rotation ofsonic connector 52, housing 42 and cavity 202 also prevent free rotationof ultrasound transmission member 24, which is securely coupled withsonic connector 52. Conversely, if rotation of ultrasound transmissionmember 24 is desired, a user of device 10 can rotate housing 42, such asby rotating it in his/her hand, and this rotation of housing 42 will betransmitted to sonic connector 52 and ultrasound transmission member 24.

Returning to FIG. 3, middle segment 45 of bore 44, in some embodiments,may surround a portion of sonic connector 52, while in otherembodiments, sonic connector 52 may be housed only within proximalsegment 47. Sonic connector 52 is coupled with the proximal end ofultrasound transmission member 24 by any suitable means for transmittingultrasound energy to transmission member 24 from transducer 14. Absorbermembers 50, such as O-rings, surround a portion of ultrasoundtransmission member 24 for providing absorption of transverse vibration.Absorber members 50 may be used in any number or combination and haveand suitable size and configuration, depending on the desired level ofvibration absorption or dampening. Alternatively or additionally, otherdampening structures may be used. Thus, the invention is not limited tothe combination shown in FIG. 3.

Distal segment 49 of bore 44 typically surrounds a portion of ultrasoundtransmission member 24 and may also contain one or more additional setsof absorber members 50. Distal segment 49 may also contain a portion ofa Y-connector 11, which is coupled with the distal end of housing 42.Coupling of Y-connector 11 with the distal end of housing 42 may beaccomplished via complementary threads, pressure fitting, or any othersuitable means. A Y-connector lumen 48 of Y-connector 11 allows passageof ultrasound transmission member 24 and is in fluid communication withcatheter body lumen 21.

Generally, pressurized fluid such as a coolant liquid may be infusedthrough a side-arm 13 of Y-connector, through Y-connector lumen 48 andthrough catheter body lumen 21 so that it flows out of one or more fluidoutflow apertures in distal head 26. The temperature and flow rate ofsuch coolant liquid may be specifically controlled to maintain thetemperature of ultrasound transmission member 24 at a desiredtemperature within its optimal working range. In particular, inembodiments of the invention wherein ultrasound transmission member 24is formed of a metal alloy which exhibits optimal physical properties(e.g. super elasticity) within a specific range of temperatures, thetemperature and flow rate of coolant liquid infused through fluidinfusion side-arm 13 may be specifically controlled to maintain thetemperature of ultrasound transmission member 24 within a range oftemperatures at which it demonstrates its most desirable physicalproperties. For example, in embodiments of the invention whereinultrasound transmission member 24 is formed of a shape memory alloywhich exhibits super elasticity when in its martensite state, but whichloses super elasticity as it transitions to an austenite state, it willbe desirable to adjust the temperature and flow rate of the coolantliquid infused through fluid infusion side-arm 13 so as to maintain theshape memory alloy of ultrasound transmission member 24 within atemperature range at which the alloy will remain in its martensite stateand will not transition to an austenite state. The temperature at whichsuch shape memory alloys transition from a martensite state to anaustenite state is known as the “martensite transition temperature” ofthe material. Thus, in these embodiments, the fluid infused throughside-arm 13 will be at such temperature, and will be infused at suchrate, as to maintain the shape memory alloy of ultrasound transmissionmember 24 below its martensite transition temperature.

Referring now to FIGS. 4A and 4B cross-sectional side views of oneembodiment of the coupling of proximal connector 12 with the distal endof a transducer device 400. Generally, transducer device will include atransducer housing 402, piezoelectric crystals 404, a transducer horn406, and any suitable coupling means 412 for coupling transducer horn406 with sonic connector 52. Coupling means 412 may include, forexample, complementary threads, a pressure fitting configuration or thelike. In some embodiments, transducer housing 402 includes a slidablecollar 408 and at least one surface protrusion 410. Surface protrusion410 generally fits over the outer surface of housing 42 of proximalconnector 12. In some embodiments, as shown in FIGS. 4A and 4B,protrusion 410 may be a ring surrounding a portion of transducer housing402, though any other configuration is contemplated. Slidable collar408, in turn, is slidable between an unengaged position, as in FIG. 4A,and an engaged position, as in FIG. 4B. In the engaged position,slidable collar 408 fits around the outer diameter of protrusion 410sufficiently tightly to apply pressure against protrusion 410. Thispressure presses protrusion 410 against housing 42 to further securetransducer housing 402 to proximal connector 12. This further securingprevents unwanted separation of ultrasound catheter device 10 fromtransducer device 400. Any other suitable configurations, shapes, sizesand the like of collar 408 and protrusion 410 are contemplated.

With reference now to FIGS. 5A and 5B, ultrasound catheter device 10 isshown coupled with transducer housing 402. FIG. 5A shows slidable collar408 in its unengaged position, while FIG. 5B shows collar 408 in itsengaged position. In some embodiments, protrusion 410 may be a ringmaking up or surrounding a portion of transducer housing 402, asmentioned above. Also in some embodiments, protrusion 410, such as aring, may include a slot 414 or other opening, which may go through allor part of the thickness of protrusion 410. Slot 414 generally allowsprotrusion 410 to give or bend when collar 408 is fitted over protrusion410, thus reducing the inner diameter of protrusion 410 to press againstthe outer surface of proximal connector device 12. Again, any suitableconfiguration for slot 414 is contemplated within the scope of thepresent invention. When collar 408 is engaged, as shown in FIG. 5B,transducer housing 402 or proximal connector 12 may be rotated, andultrasound catheter device 10 (with ultrasound transmission member 24)will rotate in turn. Such rotation may be accomplished even when collar408 is in the unengaged position (FIG. 5A), but collar 408 andprotrusion 410 enhance coupling of transducer housing 402 and proximalconnector 12, to provide additional control and to assure thattransducer housing 402, proximal connector 12 and the rest of ultrasoundcatheter device 10 either rotate together or do not rotate.

Referring now to FIGS. 6-8, various embodiments of a distal end ofultrasound catheter device 10 are shown within a blood vessel 430,adjacent an occlusion 432. Various embodiments of ultrasound catheterdevice 10 include one or more expandable members 422, such as balloons,as well as one or more fluid apertures 426 in distal head 26. Someembodiments may also include, or may be used in conjunction with, aguide catheter 420 having a guide catheter aperture 421. In oneembodiment, as shown in FIG. 6, fluid may be introduced adjacentocclusion 432 via fluid apertures 426 and/or guide catheter aperture421. Once catheter device 10 has begun to break occlusion 432 intomultiple fragments 428, fluid (either by itself or containing thefragments) may be removed from blood vessel 430 via fluid apertures 426and/or guide catheter aperture 421. In FIG. 6, fluid is being introducedvia guide catheter aperture 421 (arrows), and fluid and fragments 428are being removed via fluid apertures 426. The opposite may also bepossible. Such fluid introduction and fluid/fragment removal areenhanced in some embodiments by expanding a balloon 422 proximal to thefluid introduction/removal apertures. In the embodiment shown in FIG. 6,balloon 422 is coupled with guide catheter 420.

With reference to FIG. 7, in an alternative embodiment, balloon 422 iscoupled with catheter body 22 rather than guide catheter 420. In thisembodiment, fluid may be introduced by one or more fluid apertures 427and fluid and fragments 428 may be removed via one or more other fluidapertures 426. Generally, any suitable combination of fluid apertures426, 427 for infusion of fluids and/or aspiration of fluids and/orparticles may be used. In yet another embodiment, and with reference nowto FIG. 8, ultrasound catheter device 10 may include a sheath 424 aroundits outer circumference, the sheath forming a sheath aperture 425.Sheath aperture 425 may then be used for fluid introduction and/orremoval of fluid/fragments 428. In FIG. 8, for example, fluid is shownexiting fluid apertures 426 and entering sheath aperture 425 (arrows).Virtually any suitable combination of apertures and expandable membersis contemplated by the present invention. The use of apertures andexpandable members generally enhances operation of ultrasound catheterdevice in breaking down occlusions and removing occlusion fragmentsharmlessly from the patient.

With reference now to FIGS. 9-11, various embodiments of the distal endof ultrasound catheter device 10 are shown in cross-sectional side viewsuitably includes an elongate catheter body 22 with at least one hollowcatheter body lumen 21. In FIGS. 9-11, catheter body 22 is shown havingone lumen 21, but it may have any number of lumens in variousembodiments. Disposed longitudinally within catheter body lumen 21 arean ultrasound transmission member 24 and a hollow guidewire tube 28forming a guidewire lumen 29. Coupled with the distal ends of ultrasoundtransmission member 24 and guidewire tube 28 is a distal head 26,positioned adjacent the distal end of catheter body 22.

Generally, the various coupled components described above may be coupledby any suitable means, such as adhesives, complementary threadedmembers, pressure fittings, and the like. For example, distal head 26may be coupled with ultrasound transmission member 24 and guidewire tube28 with any suitable adhesive substance or via welding, bonding or thelike. Adhesives used to attach guide wire tube 28, distal head 26 and/orcatheter body 22 may include, but are not limited to cyanoacrylate (eg.Loctite™, Loctite Corp., Ontario, CANADA or Dron Alpha™, Borden, Inc.,Columbus, Ohio) or polyurethane (e.g. Dymax™, Dymax EngineeringAdhesive, Torrington, Conn.) adhesives. In some embodiments, guidewiretube 28 may also be coupled with catheter body 22 by adhesive, weldingor other means. Some embodiments may also include one or more anchoringmembers for further securing distal head 26 to the ultrasound catheterdevice 10 and to help ensure that distal head 26 does not break free ofcatheter device 10.

For example, referring to FIG. 9, in one embodiment an anchoring member440 may be connected at one end to distal head 26 and at the other endto catheter body 22. Again, any connection means may be used, such asbut not limited to adhesives, welding, bonding and/or the like.Furthermore, anchoring member 440 may be connected to distal head 26 andcatheter body 22 at any suitable locations. Another embodiment is shownin FIG. 10, in which anchoring member 440 is coupled with distal head 26and guidewire tube 28. This connection may provide similar safety andprevention of distal head 26 migration. Finally, in some embodiments, asshown in FIG. 11, guidewire tube 28 itself acts as an anchor, and aseparate anchoring member is not used. Any suitable configuration andcombination is contemplated by the scope of the present invention.

Finally, and with reference now to FIGS. 12A-12C, one embodiment of anultrasound transmission member 24 and a method for making same is shown.In this embodiment, ultrasound transmission member 24 is made from aunitary piece of precursor material 450 and includes distal head 26.Thus there is no separate distal head piece that is attached toultrasound transmission member 24—instead it is all one piece.Generally, ultrasound transmission member 24 may be formed of anymaterial 450 capable of effectively transmitting ultrasonic energy fromultrasound transducer 14 to the distal end of catheter body 22,including but not limited to metals such as titanium and nickel alloys.

In accordance with one aspect of the invention, all or a portion ofultrasound transmission member 24 may be formed of one or more materials450 which exhibit superelastic properties. Such material(s) 450 shouldpreferably exhibit superelasticity consistently within the range oftemperatures normally encountered by ultrasound transmission member 24during operation of ultrasound catheter apparatus 10. For example, insome embodiments, material 450 is an alloy having a tensile strength ofbetween about 170,000 Psi and about 250,000 Psi. In some embodiments,the alloy exhibits elongation of between about 7% and about 17%. Forexample, in some embodiments the alloy is a nickel-titanium alloy havingnickel content of between about 50.50 and about 51.50 atomic weight.

Use of supereleastic metal alloys in ultrasound transmission members isdescribed in U.S. Pat. No. 5,267,954, previously incorporated byreference. Examples of superelastic metal alloys which may be used aredescribed in detail in U.S. Pat. No. 4,665,906 (Jervis); U.S. Pat. No.4,565,589 (Harrison); U.S. Pat. No. 4,505,767 (Quin); and U.S. Pat. No.4,337,090 (Harrison), the entire disclosures of which are herebyincorporated by reference insofar as they describe the compositions,properties, chemistries and behavior of specific metal alloys which aresuperelastic within the temperature range at which ultrasoundtransmission member 24 of the present invention operates, any and all ofwhich superelastic metal alloys may be used to form ultrasoundtransmission member 24 of the present invention. In some embodiments,for example, the alloy exhibits a superelastic temperature range ofabout 10 degrees Celsius to about 50 degrees Celsius.

In many embodiments, ultrasound transmission member 24 includes a widerregion 452 toward its proximal end and one or more tapered regions 454towards its distal end. Tapered region 454 decreases the distal rigidityof ultrasound transmission member 24, thus amplifying ultrasound energytransmitted along ultrasound transmission member 24 to distal head 26.Distal head 26 may have any suitable configuration, shape, and sizesuitable for ablating or otherwise disrupting occlusions. For example,distal head 26 may have a shape that is bulbous, conical, cylindrical,circular, rectangular or the like. Similarly, distal head 26 may havedimensions which allow it to fit wholly or partially within the distalend of catheter body lumen 21 or may, alternatively, be disposedcompletely outside catheter body lumen 21. Thus, the configuration ofdistal head 26 may take any suitable form and should in no way belimited by the exemplary embodiments pictured in FIGS. 12A-12C.

In one embodiment, a method of making ultrasound transmission member 24involves providing transmission member precursor material 450 (FIG.12A), removing some of material 450 by any suitable process to formtransmission member 24 and distal head 26 (FIG. 12B), and then removingadditional material from distal head to form one or more fluid apertures426 (FIG. 12C). Removing material to form transmission member may beperformed via any suitable method, such as sanding, grinding, cutting orthe like. Similarly, removing material to form apertures 426 may beperformed via any suitable method, such as boring through distal head26. Any analogous methods are contemplated within the scope of theinvention.

Although the invention has been described above with specific referenceto various embodiments and examples, it should be understood thatvarious additions, modifications, deletions and alterations may be madeto such embodiments without departing from the spirit or scope of theinvention. Accordingly, it is intended that all reasonably foreseeableadditions, deletions, alterations and modifications be included withinthe scope of the invention as defined in the following claims.

1. A method for disrupting an occlusion in a blood vessel, the methodcomprising: positioning an ultrasound catheter in the blood vessel suchthat a distal end of the catheter is adjacent the occlusion;transmitting ultrasound energy to an ultrasound transmission member ofthe ultrasound catheter to disrupt the occlusion into fragments;expanding an expandable balloon coupled with the ultrasound catheter ata location proximal to the distal end of the catheter; and removing atleast some of the fragments from the blood vessel via the ultrasoundcatheter.
 2. A method as in claim 1, wherein positioning the ultrasoundcatheter comprises guiding the catheter using a guidewire.
 3. A methodas in claim 1, wherein the fragments are removed through at least oneaperture in a catheter body of the ultrasound catheter.
 4. A method asin claim 3, wherein the at least one aperture is in fluid communicationwith at least one irrigation lumen and the fragments are removed throughthe at least one aperture and the at least one irrigation lumen.
 5. Amethod as in claim 3, wherein the at least one aperture is in fluidcommunication with at least one guidewire lumen and the fragments areremoved through the at least one aperture and the at least one guidewirelumen.
 6. A method as in claim 3, wherein the at least one aperture isdisposed distal to the expandable balloon.
 7. A method as in claim 1,wherein the fragments are removed through a sheath disposed around aportion of the ultrasound catheter.
 8. A method as in claim 1, whereinremoving the fragments comprises applying a vacuum to guide thefragments into at least one aperture on the ultrasound catheter.
 9. Amethod as in claim 8, wherein applying the vacuum comprises using atleast one of a syringe and a vacuum pump.
 10. A method as in claim 1further comprising introducing a fluid into the blood vessel via theultrasound catheter.
 11. A method for disrupting an occlusion in a bloodvessel, the method comprising: introducing an ultrasound catheter intothe blood vessel through a guide catheter; positioning the ultrasoundcatheter such that a distal end of the catheter is adjacent theocclusion; transmitting ultrasound energy to an ultrasound transmissionmember of the ultrasound catheter to disrupt the occlusion intofragments; expanding an expandable balloon coupled with the guidecatheter at a location proximal to the distal end of the ultrasoundcatheter; and removing at least some of the fragments from the bloodvessel via the ultrasound catheter.
 12. A method as in claim 11, whereinintroducing and positioning the ultrasound catheter further compriseguiding the ultrasound catheter using a guidewire.
 13. A method as inclaim 11, wherein the fragments are removed through at least oneaperture in the guide catheter.
 14. A method as in claim 13, wherein theat least one aperture is disposed distal to the expandable balloon. 15.A method as in claim 11, wherein the fragments are removed through atleast one aperture in the ultrasound catheter.
 16. A method as in claim15, wherein the at least one aperture is disposed distal to theexpandable balloon.
 17. A method for disrupting an occlusion in a bloodvessel, the method comprising: positioning an ultrasound catheter in theblood vessel such that a distal end of the catheter is adjacent theocclusion; transmitting ultrasound energy to an ultrasound transmissionmember of the ultrasound catheter to disrupt the occlusion intofragments; and introducing at least one radiopaque fluid into the bloodvessel through at least one aperture in the ultrasound catheter adjacentthe distal end to enhance visualization of a location of the distal end.18. A method as in claim 17, wherein introducing the radiopaque fluidcomprises introducing through at least one irrigation aperture in theultrasound catheter.
 19. A method as in claim 17, wherein introducingthe radiopaque fluid comprises introducing through at least oneguidewire aperture in the ultrasound catheter.
 20. A method as in claim17, wherein introducing the radiopaque fluid comprises introducingthrough a sheath surrounding at least a portion of the ultrasoundcatheter, the at least one aperture being formed between at least aportion of the sheath and at least a portion of the ultrasound catheter.